In many situations today a user of a communication device such as a mobile phone wants to know who's calling. To this end, makers of communication devices today typically provide a way for a user to associate with a calling number (or simply with a call irrespective of who's calling) a particular sound (including music) to serve as a ring tone. Such a ring tone could be, e.g. a portion of an audio file stored in the communication device, or at least the audio portion of an audio-video file. Users today can also use clips of audio-video files (including what are sometimes called music video files) for ring tones.
Besides wanting to know who's calling, users of communication devices today sometimes use such devices for (sending and) receiving SMS (short message service) mail, email, or other digital messages. And users can configure their communication devices to indicate the sender of an email (or simply that an email has arrived) by having the communication device emit a distinct sound to serve as what is more aptly called an alert notification, alerting the user that an email from a particular sender (or irrespective of the particular sender) has arrived. The distinct sound could be, again, a portion of an audio file.
Further, many communication devices are configurable by the user to emit a distinct sound in case of other events. A simple example is the event of a certain time, i.e. the user configures the communication device to serve as an alarm clock, and arranges that a particular sound be produced by the communication device, and again, the user might want the sound to be a portion of an audio file (or the audio portion of an audio-video file).
So there are, in principle, many different events for which a user might want to associate distinct sounds or segments/clips of audio or audio-video files. To actually store in a communication device a segment of an audio (or audio-video) file for each different possible event a user might want to be alerted to can consume a significant portion of the memory of a communication device. Thus, since in general memory in a communication device is advantageously used prudently, it would be useful to store or otherwise indicate in a communication device many different clips of audio or audio-video files (or even simply pure video), but in a way that conserves memory.